Question
Hi Tom,

I recently bought a 1/2 whiskey barrel, filled it with water and put in a pump powering a small fountain. There are no fish or other "lvestock" in the barrel. All was fine for a number of weeks. The water was clear and I was pleased with my efforts. However, I then bought a water lily, planted it in aquatic compost, and iwthing a short time a white slime started to grow at the side of the barrel, and also on the stems of the lilies and the pump itself. I had planned to try and grow some water cress in this tub at some stage, however, with the white slime present, I am not sure if this would be a good idea.

Could you possibly give me some advice as to firstly, where you think this white slime may have come from and how I can get rid of it, and secondly whether growing water cress would be a good idea?

Many thanks

Stephen

Answer
Hi Stephen,
Thanx for your questions.  I've not dealt with a white slime problem before.  Sometimes certain cleaning products that may have been used to clean the whiskey barrel before it was sold to you could have embedded sulphur and other chemicals into the wood which would leach out once the barrel was filled with water and had a chance to sit.  If there are zinc nails in the barrel this could contribute to chemicals that cause certain slime molds to grow.  The lily could have introduced it into the water.  You may want to let the slime progress as they usually cure themselves but if after a few weeks it doesn't seem to be disappearing visit your local nursery that deals with water gardens and ask for a chemical to eradicate the slime.  I don't like using chemicals myself except as a last resort.  I don't think I would introduce the watercress just yet.  The white slime is something I have not encountered as a result of plant growth or at all for that matter.  Let the water garden continue to age and see if that doesn't take care of the problem first.  Check in with me again if it doesn't and I'll see what else I can find.  I hope this helps.
Tom